3.5 Sediment Chemical Analysis 



The results of the sediment chemical analyses of the Top 

 and Bottom sections of the cores from the replicate grab samples 

 were presented for each disposal mound and the reference station 

 (Tables 3-1 through 3-19) . In the case of PCBs, only one composite 

 sample was analyzed from each station. With the exception of Hg 

 at Norwalk Center (Table 3-9) , mean concentrations were at 

 'Moderate' levels or lower for all mound and reference stations 

 sampled, compared to the New England River Basin Commission's 

 (NERBC) interim criteria (NERBC, 1980) . At Norwalk Center, both 

 Top and Bottom core section samples exceeded the 1.5 ppm upper 

 limit for 'Moderate' levels of Hg, because of particularly high 

 concentrations detected in one individual replicate (2.44 ppm in 

 one Top replicate and 4.15 ppm in one Bottom replicate). However, 

 both Top and Bottom samples at this station had at least one 

 replicate with Hg results below the 'Moderate' upper limit. 



'Low' levels or lower were detected for all parameters 

 at CLIS reference, CS-1 Center, CS-2 Center, STNH-S Center, and 

 most of the STNH-N stations. At STNH-N stations 100N, 200N, and 

 400E, 'Moderate' levels of Hg were detected in Top and/or Bottom 

 samples, and 'Moderate' levels of Pb where detected in the Bottom 

 sample of station 200E. At FVP Center, MQR Center, CLIS-86 Center, 

 NH74 Center and Norwalk Center, levels of Hg, Pb, Zn, Cr, Cu and 

 PCBs generally fell within the 'Moderate' category in both Top and 

 Bottom samples. (The State of Connecticut doesn't have a 

 classification for PCBs; however Massachusetts has values of <0.5 

 for 'Low'; 0.5-1.0 for 'Moderate'; and >1.0 for 'High'). All the 

 other metal and PCB concentrations at these stations were at 'Low' 

 levels. 



Statistical comparisons revealed that for most parameters 

 at most of the stations sampled there was no significant difference 

 between levels detected in the Top and Bottom core sections (Table 

 3-20) . The exceptions included MQR Center, STNH-S Center, and NH74 

 Center, which showed significantly greater elevations in the Bottom 

 samples for some of the trace metals and percent total carbon. At 

 STNH-N Center, concentrations of Pb, As, and Fe were significantly 

 elevated in the Top of the core section (Table 3-20) . 



In comparisons of the Top 2 cm samples, every parameter 

 tested was significantly elevated at MQR compared to the reference 

 station (Table 3-21) . FVP, CLIS-86, NH74 and Norwalk showed levels 

 elevated from reference for approximately half of the parameters 

 tested, while the other mounds showed only a scattering of 

 parameters with levels elevated from reference (Table 3-21) . 

 Statistics for the Bottom core section samples more clearly 

 identified MQR, FVP, and NH74 to be mounds consistently elevated 

 from reference in all or almost all parameters tested. NH-83, 

 Norwalk, and CLIS-86 also showed significantly greater 

 concentrations than reference in many of the trace metals, total 



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